Podcast 209: Exterior Caulk, Tub Drains, and Adding Insulation to Leaky Walls
Matt, Rob, and Kiley discuss the best exterior sealants, how to take apart a tub drain, and how to insulate existing walls with fiberboard sheathing and a vapor barrier.
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The crew hears from Rob about a very cool training lab for weatherization work. Cooper shows off his newly-completed garage air sealing and insulating project. Jeff describes how industrial gas bottles are safety tested and he talks about some very interesting bottles dating from the earliest days of rocketry. Cole gives his secrets for installing dog doors meant for entry doors. Daniel wants to know who makes the best outdoor caulk. Kevin wants to know the best plan for an efficient house in South Carolina. Brandon asks how to take apart his tub drain so he can replace the tub. Finally Byron wants to know how to safely insulate his walls which have fiberboard sheathing on the outside and a foil vapor barrier (FSK) on the inside.
Listener feedback #1
Rob writes, Hello all, When you read my letter on the podcast a while back you had asked for some pictures of the Indoor Climate Research and Training Center at the University of Illinois. It’s where most of us who work for the Illinois Home Weatherization Assistance Program go for our 10 week certification program. Yesterday was National Weatherization Day and the training center hosted an open house, that’s Bill Rose standing in the doorway of pic 2, so I was able to grab some photos for you. The center has various props used to demonstrate pressure imbalances, stack effect, spillage etc. The tiny house can be setup in a multitude of different pressure scenarios and it’s where we take our field tests for BPI certifications. When taking a field test you never know how the house is going to be setup and what result the setup will have on things like natural draft appliances, etc. The furnace lab can also be configured to show what happens when things like static pressure, gas flow, and temperature rise are not in alignment and the effect it has on the units efficiency and occupant comfort. Hope all is well and keep up the good work!
Listener feedback #2
Cooper writes, Hello FHB Podcast crew! Way back in Episode 132 you all were kind enough to air my video question and provide some helpful advice. As Patrick requested, I’m finally following up to let you know how it went. It took about a year, but I did make the garage completely outside the conditioned envelope as was suggested. A few of the things I ended up doing were:
- Removing all the duct work and cleaning and properly sealing it all with mastic and tape.
- Building new ducts to replace the joist span returns and fit those inside the joist bays.
- Wrapping the ducts in insulation, then building soffits and further insulating those with Rockwool and foam.
- Removing the small hollow-core entry door that had gone to the basement and re-framing a new wall in front of that so I could add more insulation.
- The ceiling got R-38 fiberglass batts and 2″ XPS that was foamed and taped to completely seal it. I even used ZipTape to seal the foam to the metal I-beam in the center.
- The walls got 2×4 Rockwool and 1.5″ XPS all over. Then I put up strapping and covered everything with 5/8 Type X drywall. I used FibaFuse tape and thought it was so much easier for a novice drywaller.
I’m attaching a few pictures from the process, and here is a link to the larger online album. Feel free to share if my process is helpful to any other listeners with similar under-house garages, I welcome all questions and feedback.
Listener feedback #3
Jeff from California writes, Howdy Fine Homebuilding Team, Love the show! Thought I would offer up some trivia after Patrick’s “old” oxygen tank comment. Many pressure vessels for gasses (K bottles) are indefinitely serviceable as long as they pass testing and/or inspection. Now for the trivia.
Once upon a time I worked on the shuttle program at Kennedy Space Center where we employed thousands of nitrogen K-bottles for purging hazardous areas such as around rocket fuel. Purging is basically pumping nitrogen or helium into high risk locations such as light switches or electric motors to prevent catastrophic, life ending explosions. Most of their bottles dated to the mid thirties…yes, I said 30’s! Let see, what was going on in the thirties….oh yeah, WWII, and who was playing with lots of rockets in the 30’s? Survey says, Nazis!
You probably figured it out by now but some of the nitrogen bottles used in the U.S. space program are former Nazi bottles. At the end of WWII the U.S. and Russia scooped up German scientist and rocket technology including thousands of these bottles that are still in use today. Since each bottle was marked with a Nazi swastika, most maintenance shops turned the swastika into a four pane window by adding a few more punch marks. Creepy right?
Well, keep up the great work….I have to go air-seal a spaceship now (kidding).
- Repurposed WWII German welding-gas cylinders (from www.chemistry-blog.com)
- Welding – Storage and Handling of Compressed Gas Cylinders (from www.ccohs.ca)
Listener feedback #4
Cole writes, I wanted to weigh in on your discussion of doggy doors. Someone mentioned that you can put them in a wall instead of an entry door. I have done a few of these and used ½’-in Azek (cellular PVC) sheet stock to make a boxed extension jamb. The Azek is easy to clean and because it’s white usually matches the frame.
Cut the opening, build and install the box, flash the outside according to siding type, install the finish frames and seal all penetrations. Some of the frames may need slight modification for mounting because they snap together in a male/female arrangement. I usually back the frame with urethane based sealant and attach it to the extension jamb with #6 stainless pan head screws. Most pet doors work well with 16’’ on-center framing.
Kiley: New tap dance surface
Patrick: Replacing a fence post with Liam and blowing insulation with Matt
Question 1: What are the best caulks for exterior siding/trim work and interior trim work?
Kevin writes, Hi all, I am a frequent listener and fan of the podcast. Thanks for the work you do and helping people figure out the correct way to build things! In regards to the listener a few podcasts back who complained that what you present isn’t applicable to California, I somewhat disagree. While you may get a little further in to insulating and air-sealing than is necessary for our climate, it seems as if it is the correct way to do things and just because we can get away without doing it doesn’t mean we should.
My question is pretty simple; what are the BEST caulks for exterior siding/trim work and interior trim work?
A little background to the question:
My wife and I are currently in the process of building a house as owner-builders. Prior to starting construction on the house, we built a small outbuilding near our house to protect our transformer and serve as a trial run for how we think we wanted to build the house. This resulted in a pretty nice 12′ x 14′ building complete with Hardie Lap siding. trim, and soffits, and an interior with crown molding and window casings.
At the time that we were caulking everything before painting, I was torn between quality and price (now I don’t care about price). For the interior, I used ALEX Plus… in retrospect, I realize this isn’t even close to the top of the list as far as quality, and when I now see it pulling away from the crown molding a year later I am really not surprised. Any suggestions on what makes a long-lasting, easily-tooled caulk for interior trim is greatly appreciated.
On the exterior, we approached caulking in a more scientific way: We ran a trial between DAP 3.0, OSI Quad, and Gorilla Glue caulk. We found that while the DAP had a quick drying time, it was very difficult to tool. Gorilla Glue made the best caulk as far as dry time and tooling, but it was what I perceived to be too expensive ($10/tube). We ended up using OSI Quad, which is also what Hardie recommends. By the time we were done with the project, I had a couple gripes about OSI Quad: First and foremost, it shrinks like heck as it drys. Second, it has an obscenely long dry-time before you can paint it. Overall, not a fan.
If Gorilla Glue hadn’t discontinued carrying their caulk at the big box stores, I wouldn’t be writing this email… I am curious to your thoughts on what would be an excellent exterior caulk? Recently, I applied some non-sag polyurethane concrete caulk (Loctite PL S10) to the groove between my pressure-treated sill plates and the concrete stem wall to impede insect entrance. While I will be the first to say tooling polyurethane is miserable, I appreciate the tenacity and longevity of the product. I see Loctite makes a window and siding polyurethane caulk as well (PL S40). Any experience with this? Maybe it is the solution I am looking for.
Thanks in advance for your time and advice.
Question 2: How can I build the most energy efficient home possible in South Carolina?
Daniel from South Carolina writes, Hello FHB podcast long time listener first time caller. I’m an owner builder starting on a small house build. The living space will be 16’x16’ two story’s (512 sf). I live in South Carolina and want to build the most energy efficient home possible but I’ve have a few questions. It will have a block sealed crawl space. I plan to frame the entire building using screws for added strength.
I plan to use zip R3 as the sheathing and I know it’s not approved but I also plan to use it on the roof as well screwed down with 2 1/2” decking screws. Thoughts? The plans I have call for 2×4 walls so I will be insulting with rock wool insulation. I will be siding the house with poplar bark siding. What would you recommend I use to create a drainage gap behind that? I’ll be using metal roofing as well. Should that be vented as well?
It will be heated and cooled with a mini split. To summarize my questions are:
- How do I go about encapsulating the crawl space correctly?
- What do I use behind the siding as a drainage gap?
- Does the roof need venting?
- And with a tight envelope will I need an ERV and if so what do you recommend?
Thank you for a great podcast and magazine.
- Video: How to Install a Ventilated Rainscreen
- Jake Bruton: 3/8-in. plywood is my favorite rainscreen material
- Creating a Sealed Crawlspace
Question 3: What type of connection is standard for tub to waste line?
Brandon writes, Hey there- I’m looking to install a new bath tub in the guest bathroom of my condo unit built on slab on grade. I’ve never done one but I would consider myself a decent enough DIYer that I could tackle this project. I’ve been doing a lot of research in order to understand as much of the process as possible before I gut the bathroom, but one thing I haven’t been able to find out is how the bath drain line ties into the waste line. Getting the connection right is a huge concern of mine since our unit has had an unfortunate history of sewer line back ups. I think that the issues are resolved now but Im not interested in finding out the hard way.
Question 1: What type of connection is standard for tub to waste line? Is it a screw together connection with a gasket or some sort of seal?
- Drain/Overflow Assemblies
- Fix Your Tub Drain
- Watco FLEX Lift & Turn Flexible PVC with Schedule 40 Sanitary Tee
- Help Tying Into a Drain Line
Question 4: How can I safely insulate existing walls that have brick veneer and vapor-permeable sheathing?
Byron writes, Hello Fine Homebuilding (Air Sealing) Podcast Team. First off, thanks for the great information and entertainment. I am glad to know there are people out there that like to talk about air sealing and insulating as much as I do. 🙂
Anyway here is the situation. I have a 1960’s tri-level, it has no meaningful insulation in the walls (see the attached sketch and picture for details on the wall build up). From the inside out, it is 50+ years of paint, sheet rock, empty 2×4 cavity, FSK, asphalt impregnated sheathing, cedar siding, perforated 1/8″ foam insulation, vinyl siding. There is horizontal 2×4 blocking in the cavity at about 48″ above the floor. I live in Richmond Virginia so the climate is Mixed – Humid according Building Science Corp and ASHRAE Climate Zone 4A.
As I have been doing remodel projects when the walls are opened up I remove the FSK, insulate and air seal as well as possible from the inside. However, we are about to start a larger remodel project where I will have an opportunity to temporarily pull the vinyl siding off for most of the house. While I have it off, I want to insulate to improve comfort and reduce the heat loss by drilling holes and densepacking insulation from the outside. The current project scope does not include removal of the interior sheet rock or the cedar siding.
Do you have any recommendations?
Is there another option other than drill and blowing that you would recommend?
What type of insulation do you recommend?
I am looking for good enough to not rot the walls or break the bank. Budget wise, I am leaning toward blown in cellulose or rockwool.
I am concerned about the FSK in the wall as it is vapor impermeable and it could trap moisture in the wall. I will not be able to get to the theoretical air barrier below the cedar siding (asphalt impregnated sheathing) to seal the seams and edges when doing the insulation so I am concerned about hot humid air leaking into the cavity.
Thanks for the help!
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